The present invention relates in general to microwave ovens and more particularly to a beam stirrer used in the microwave oven for providing a more uniform heating pattern.
In order to provide uniform and rapid heating of materials and foods, high frequency energy, generally in the microwave region, has been utilized. Materials or foods to be heated are generally placed in an enclosure which is sealed to prevent the escape of high frequency energy. The energy generated, usually from a magnetron, is inserted either directly into the enclosure or indirectly through the use of a waveguide or other suitable coupling device.
Mode stirrers are well known in the art and are shown, for example, in U.S. Pat. No. 3,106,629. Although these mode stirrers do provide somewhat of an improvement in the uniformity of the heating pattern, there are certain disadvantages associated with these prior art structures. For example, there is generally a matching problem between the cavity and the magnetron which is occasioned by the abrupt discontinuity that occurs each time the blades of the stirrer rotate across the mouth of the waveguide opening.
Accordingly, one object of the present invention is to provide an improved structure for location within a microwave oven for providing a uniform heating pattern.
Another object of the present invention is to provide a beam stirrer for use in a microwave oven and that is in the form of a resonant structure capable of providing good matching with the magnetron.
A further object of the present invention is to provide a beam stirrer in accordance with the preceding object and that is moveable in an eccentric manner to provide beam motion over an area of the oven.